Embodiments of the inventive concept described herein relate to an apparatus for measuring fine particulate matter and a method thereof, and more particularly, relate to technologies of determining a time to replace each of a filter and an air quality sensor based on a concentration of transmitted fine particulate matter.
Fine particulate matter (PM2.5) which exists in the air is injurious to the human body since its particles are smaller than those of particulate matter (PM10). This is introduced into blood through lungs. Long-term exposure to fine particulate matter may cause death due to lung diseases and cardiovascular diseases.
In general, a sensor is used to measure such particulate matter or fine particulate matter harmful to the human body.
The principle of a particulate matter sensor for sensing particulate matter includes irradiating light to particulate matter using an optical sensor (e.g., an infrared light emitting diode (IR LED)) or a laser light source, outputting light scattered by introduced particulate matter as a signal through an optical receiver (e.g., a photodiode), and determining a concentration of particulate matter according to a level of the signal.
Herein, since a conventional particulate matter sensor has a wide air inlet, there is a limit to which target materials (dust and the like), each of which has large particles, as well as particulate matter are introduced into the conventional particulate matter sensor. When target materials, each of which has large particles, are introduced into the conventional particulate matter sensor, the conventional particulate matter sensor does not classify a size of each of the particles and senses and transmits error information.
Further, since particulate matter (PM10) and target materials, each of which has larger particles than the particulate matter (PM10), are introduced together into the conventional particulate matter sensor due to the wide air inlet, it is difficult to measure only a concentration of particles which are smaller than fine particulate matter (PM2.5).
In general, a sensor for sensing particulate matter and fine particulate matter is mainly applied to an air cleaner. The air cleaner is a device which cleans indoor air polluted by dust, germs, and the like through a dust collection operation, a sterilization operation, a deodorization operation, and the like and includes a plurality of filters for cleaning the polluted indoor air.
There is a need to periodically manage and replace a filter to increase the efficiency of the air cleaner and extend the life of the air cleaner. A conventional air cleaner determines a time to replace its filter depending on any one of a running time, difference pressure, the number of rotations of its fan, and a change in quantity of light.
In detail, technologies of counting a running time counts the running time of the air cleaner and displays a time to replace the filter when an accumulated running time (e.g., 6 months, 1 year, 3 years, or the like) arrives at a predetermined time to allow a user to replace the filter. As such, since the conventional air cleaner replaces the filter depending on a running time even if a time to replace the filter varies according to an environment in which the air cleaner is installed, there is a limit to which it is difficult to replace the filter in a proper time.
Further, conventional technologies of an air cleaner for counting a running time are mainly applied to entry-level products and old products. There is a limit to which there is a need for an alarm process of an inaccurate time to replace the filter and a reset process upon replacement of the filter.